We studied the effect of pre-operative left ventricular function on prognosis after aortic valve replacement for aortic regurgitation. We performed echocardiography and radionuclide angiography on 94 consecutive patients undergoing operation from 1976 to 1983. For all patients, the five year survival was 84 + 5%, significantly better than our results for 1972-1976. Pre-operative resting left ventricular ejection fraction and fractional shortening were the most significant predictors of survival (p Less than .001 by univariate life table analysis). 5 year survival was 71 + 9% in patients with subnormal ejection fraction compared to 95 + 3% with normal ejection fraction. By multivariate analysis, left ventricular diastolic and systolic dimensions were also significant predictors of postoperative survival (p Less than .01). Survival was not influenced by the type of intra-operative myocardial preservation, nor did the type of myocardial preservation alter the influence of left ventricular function on prognosis. Hence, despite improved operative techniques and better long term survival compared to earlier results, preoperative resting left ventricular dysfunction continues to identify patients with aortic regurgitation at risk of death after aortic valve replacement.